Photoprints coated with polymeric ultraviolet light barrier coatings



United States Patent O US. Cl. 117--33.3 12 Claims ABSTRACT OF THEDISCLOSURE Disclosed herein are photoprints which are coated withrearrangeable polyesters which are the polymeric reaction product of (1)an aromatic dihydric compound such as the ester derivatives of4,4-bis(4-hydroxyphenyl)pentanoic acid wherein there is at least oneunsubstituted position ortho to the aromatic hydroxyl groups and (2) anaromatic dicarboxyl compound. The outer exposed surface of the polyestercoating rearranges under the influence of ultraviolet light to aifordexcellent ultraviolet light protection to the coated photoprints.

CROSS-REFERENCES TO RELATED APPLICATIONS This application is a divisionof copending application Ser. No. 470,572, filed July 8, 1965, now USPatent No. 3,444,129.

BACKGROUND OF THE INVENTION Field of the invention The present inventionrelates to photoprints that are coated with aromatic polyesters capableof absorbing utraviolet light and acting as a barrier to ultravioletlight. More particularly the present invention relates to photoprintsthat are coated with solutions of aromatic polyesters, thin films ofwhich are transparent and which will undergo rearrangement in thepresence of ultraviolet light to form a transparent compound which isstable to and will act as a barrier to ultraviolet light. Photoprintsthus coated will be protected from the harmful effects of ultravioletlight and retain their colors and clarity for longer than uncoatedphotoprints.

Description of the prior art Ultraviolet light is that portion of thespectrum just beyond violet on the short wave length side, generallyfrom 180 to 390 m Ultraviolet light is emitted by sunlight, carbon arclamps, mercury vapor lamps, tungsten arc lamps and other light sources.The invisible rays from the ultraviolet region can induce chemicalactivity which is both beneficial and/ or adverse. Some of the adverseeffects of ultraviolet light are degradation of synthetic resins, suchas polyvinyl chloride, used in exterior structures and articles exposedto sunlight, including rear windows used in convertible automobiles andthe like; fading or discoloration of white or dyed synthetic and naturaltextiles; fading or deterioration of cellulosic materials such as wood,paper, and the like; tarnishing and discoloration of metals; fading ofblack and white and colored photographic prints; fading anddiscoloration of paints, etc. Indeed, the full list of adverse effectsof ultraviolet light is too numerous to be set forth here.

Some aromatic polyesters currently available atford some partial degreeof protection. These materials are 3,506,470 Patented Apr. 14, 1970inadequate by virtue of the fact that they either have undesirable coloror they are not opaque to ultraviolet light, or more likely, theythemselves are subject to ultraviolet light degradation.

Some polymeric products have shown properties which indicate that theywould function as good ultraviolet barriers, however, the use of theseproducts is not practical because of their poor solubilitycharacteristics. They cannot be dissolved in solvents in sufi'icientquantity which would allow them to be coated onto photoprints. Likewise,they cannot be applied in a molten state or ex truded onto photoprintsbecause of their high melting point, etc.

SUMMARY OF THE INVENTION The present invention is directed tophotoprints coated with rearrangeable polyesters which are soluble inorganic solvents at room temperature and which are the polymericreaction products of an aromatic dihydric compound and an aromaticdibasic acid. The preferred dihydric compounds are the ester derivativesof 4,4-bis(4-hydroxyphenyl)pentanoic acid wherein there is at least oneunsubstituted position ortho to the aromatic hydroxyl group.

Upon exposure to ultraviolet light the exposed outer surface of thepolyester rearranges to form a coating ofpoly-(orthohydroxybenzophenone) units or analogs thereof which iscapable of acting as a stable barrier to ultraviolet light therebyprotecting the coated photoprint from the harmful effects of ultravioletlight.

The primary object of this invention is to provide coated photoprintswhich will be resistant to the adverse effects of ultraviolet light.

Another object of this invention is to provide a photoprint coated withtwo contiguous, superposed layers; one of which is formed by therearrangement of the polyester layer and is capable of renewing orregenerating itself from the polyester layer.

Another object of this invention is the provision of a method of coatingphotoprints with aromatic polyesters which act as a barrier againstultraviolet light.

The foregoing and other objects are attained by coating the photoprintsto be protected with a solution of a rearrangeable polyester having amolecular weight in the range of from 3,000 to 200,000 which comprisesthe polymeric reaction product of:

(A) From 10 to parts, based on a total of 100 parts of (A) and C), of anaromatic dihydric compound having at least one unsubstituted positionortho to an aromatic hydroxyl group wherein the aromatic dihydriccompound corresponds to the general structural formula:

HO R OH wherein R is selected from the group consisting of hydrogen andalkyl groups of from 1 to 6 carbon atoms, R is an alkylene group of from1 to 10 carbon atoms and R is selected from the group consisting ofamino, alkoxys of from 1 to 18 carbon atoms, OR

radical of from 2 to 10 carbon atoms, and n is an integer of from 1 to8; and

(B) At least one aromatic dicarboxyl compound capable of esterification,which is selected from the group consisting of aromatic dicarboxylicacids and acid halide derivatives thereof which are selected from thegroup consisting of unsubstituted and halo and alkyl substituted (1)terephthalic acid, isophthalic acid, diphenic acid, bi-

naphthyl dicarboxylic acid; (2) the acid halides of the foregoing acids;and (3) acids and acid chlorides which correspond to the generalstructural formula:

X- i-X where X is selected from the group consisting of hydroxyl orhalide and R is selected from the groupconsisting of methylene,carbonyl, oxygen, sulfur, sulfone,

isopropylidene, isobutylidene and ethylidene; and

(C) From zero to 90 parts, based on a total of 100 parts of (A) and (C),of an aromatic dihydric compound selected from the group consisting of(1) an aromatic dihydric compound having at least one unsubstitutedposition ortho to an aromatic hydroxyl group, wherein the aromaticdihydric compound corresponds to the general formula:

HO R7 OH wherein each R is independently selected from the groupconsisting of hydrogen and alkyl groups of from 1 to 8 carbon atoms; and(2) a dihydric phenol,

the total quantity of (A) and (C) being substantiallystoichiornetrically equivalent to the quantity of (B).

Examples of aromatic dihydric compounds corresponding to structuralFormula I above are: 4,4-bis(4'-hydroxyphenyl)pentanoic acid;5,5-bis(4'-hydroxyphenyl)pentanoic acid; 4,4 bis(4hydroxyphenyl)hexanoic acid; 4,4- bis(4 hydroxyphenyl)heptanoic acid;4,4 bis(4'- hydroxyphenyl)octanoic acid; 4,4-bis(4'-hydroxyphenyl)nonanoic acid; 4,4-bis(4-hydroxyphenyl)decanoic acid;5,5-bis(4'-hydroxyphenyl)hexanoic acid;5,5-bis(4-hydroxyphenyl)heptanoic acid; 5,5-bis(4-hydroxyphenyl)nonanoic acid; 5,5-bis(4'-hydroxyphenyl)decanoie acid;6,6-bis(4-hydroxyphenyl) decanoic acid, etc.

Especially useful are the esters of the above mentioned acids such asthe methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, nonyl,decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl,heptadecyl, octadecyl, esters of 4,4-bis(4'-hydroxyphenyl)pentanoicacid, 5,5-bis- (4--hydroxyphenyl)pentanoic acid, etc.

Other esters include those which are the reaction product of the abovementioned acids and hydroxyl bearing compounds such as 2-ethoxyethanol,2-butoxyethanol, 2- hexoxyethanol, diethylene glycol monobutyl ether,etc. It should be obvious to one skilled in the art that some of theester derivatives may also contain ether type linkages in the aliphaticchain.

Other compounds which correspond to structural Formula I and which areuseful in the practice of this invention includeN,N-dimethyl-4,4-bis(4-hydroxyphenyl)pentamide; N,Ndiethyl-4,4-bis(4-hydroxyphenyl)- pentanamide; N methyl,N-propyl-4,4-bis(4'-hydroxyphenyl)pentanamide; N,Ndimethyl-4,4-bis(4-hydroxypheny1)decanamide; N,Ncyclohexyl-4,4-bis(4'-hydroxyphenyl)pentanamide; N,Ndicyclohexy1-4,4-bis(4-hydroxphenyl)hexanamide, etc.

Compounds corresponding to structural Formula I wherein R is an arylgroup would include phenyl-4,4-bis- (4' hydroxyphenyl)pentanoate; tolyl4,4 bis(4 by- 4 droxyphen'yl)pentanoate; phenyl 5,5 bis (4'hydroxyphenyl)decanoate, etc.

Especially preferred are the derivatives of 4,4-bis(4"-hydroxyphenyl)pentanoic acid such as the esters and amides whichpromote the solubility of the resultant polyester.

In combination with the aforementioned aromatic dihydric compounds onemay use from zero to parts, based on a total of parts of total aromaticdihydric compound of a dihydric compound of the type represented byFormula III above.

Examples of the aromatic dihydric compounds represented by the generalstructural Formula III would include the bisphenols such as bisphenol-Aor bisphenol-B or their derivatives. This group may include suchcompounds as 2,2-bis(4 hydroxyphenyl)propane; 2,2-bis(4'hydroxyphenyl)butane; 2,2 bis(4-hydroxyphenyl)-4-methylpentane; andmethyl, ethyl, propyl, butyl, amyl and hexyl esters of2,2-bis(4-hydroxypheny1)butyrate. The dihydric phenol portion may berepresented by the following compounds: resorcinol, 2,4dihydroxyacetophenone, 2- methylhydroquinone, 5-methylresorcinol,2-methylresor' cinol, catechol, hydroquinone, 4-chlororesorcinol,4-ethylresorcinol, 2-benzylresorcinol, 5-propylresorcinol,2-hexylresorcinol.

The dihydric phenolic compound may also be a fused aromatic compoundsuch as represented by dihydroxynaphthalene, dihydroxyanthracene, anddihydroxyanthraquinones. Compounds selected from these three groups musthave at least one unsubstituted position ortho to at least one of thephenolic hydroxyl groups and said phenolic hydroxyls must be capable ofbifunctional esterification to produce high polymers.

The aromatic dicarboxyl compound can be an aromatic dicarboxylic acid oran aromatic dicarboxylic acid halide or other ester-forming derivativesof the dicarboxylic acids, such as mixed anhydrides and esters of theseacids, which are free of functional groups which would interfere with orcompete with the bifunctional esterification reaction. These compoundsare represented by the terephthalic acid and isophthalic acid,halophthalic acids such as chlorophthalic, chloroisophthalic,chloroterephthalic, bromophthalic, bromoisophthalic, bromoterephthalic,alkyl substituted phthalic acids such as methyl phthalic, ethylphthalic,tertiary butylisophthalic, 2,5'-dimethylterephthalic acid, etc. Otherexamples would include tetrachloroterephthalic acid, diphenic acid,binaphthyl dicarboxylic acid and the acid chlorides and trifluoraceticmixed anhydrides and methyl and phenyl esters of all the foregoing.

Especially preferred are the acid chlorides because of their fasterrates of reactions and availability.

Equally useful are acids or acid chlorides which correspond to thegeneral structural formula:

where X may be hydroxyl or halide and R may be methylene, carbonyl,oxygen, sulfur, sulfone, isopropylidene, isobutylidene, ethylidene.Examples of compounds which correspond to this structure and which areuseful in the practice of this invention include: oxyd ibenzoic acid,butylidene dibenzoic acid, thiodibenzoic acid, isopropylidene dibenzoicacid, ketodibenzoic acd, sulfodibenzoic acid, methylene dibenzoic acid,ethylidene dibenzoic acid.

The resultant polyester is dissolved in an organic liquid solvent, thepolyester being present in an amount of 0.5% to about 75% by weight ofthe total weight of polyester and solvent. The organic solvent isselected from the groups consisting of aliphatic and aromatichalogenated hydrocarbons, aromatic and aliphatic ketones, aromatichydrocarbons, disubstit-uted acetamides, aromatic esters, aliphatic andaromatic amines, aromatic ether-s, aliphatic cyclic ethers, aromaticalcohols, aliphatic and alicyclic sulphoxides and sulphones, andunseparated alkyl aromatics. The polyester solution is applied to thesubstrate to be protected and the solvent is evaporated by any of theconventional means such as air drying, flashing the solvent off at hightemperatures or drying in vacuum.

Upon exposure to ultraviolet light the exposed outer surface of thepolyester rearranges to form a coating of poly(orthohydroxybenzophenone)units or analogs thereof, which is capable of acting as a stable barrierto ultraviolet light. Thus, it will be seen that to have this uniqueproperty of opacity to and stability to ultraviolet light thepoly(ortho-hydroxybenzophenone) must be comprised of two aromatic ringswith one ketone group between them and at least one hydroxyl group in aposition ortho to the ketone.

Coatings of these polyesters only rearrange on a thin layer of thesurface exposed to ultraviolet light, for as the rearranged structuresare formed on exposure, they block any further transmission ofultraviolet light into the coating. It is therefore the unique propertyof these coatings to replenish the poly(ortho-hydroxybenzophenones) asthese rearranged materials are gradually worn away by various conditionssuch as abrasion or ultimate chemical or physical degradation. In effectthen, the coatings comprise a reservoir system wherein a surface exposedto ultraviolet light forms a continuous thin portion of rearrangedpolymer both stable to and opaque to ultraviolet light while theremaining polyester is available to regenerate or renew a rearrangedportion when and if the protective portion is eroded or loses itsefliciency.

It is to be noted that whereas the rearranged portion is usually theouter surface of the coating on most substrates, the rearranged materialmay be the inner or under surface of the coating if the coating isplaced on the inner side of a substrate such as glass, transparent (tosome degree) to ultraviolet light. The polyester portion of the coatingin itself blocks ultraviolet light below 300 mu while the rearrangedportion extends this range to above about 400 m This screening effectmay of course overlap somewhat, and, in the case of certain rearrangedmaterials, may cut off light up to 450 me.

It appears that even a rnonomolecular film of the rearranged polymerwill afford protection of a substrate from ultraviolet light as this issubstantially a surface phenomenon. The polyester portion of the coatingmay vary in thickness depending on the substrate to be protected as Wellas the method used in applying the polyester to the substrate.

The polyesters are preferably prepared according to one of the wellknown interfacial polymerization techniques such as the method set forthby W. M. Eareckson, III, in the Journal of Polymer Science, vol. XL, pp.399-406 (1959). It is thereby convenient to polymerize rapidly at lowtemperatures in order to obtain colorless, soluble products.

Another equally useful polymerization procedure is the low temperaturesolution polymerization as described by P. W. Morgan in PolymerPreprints, vol. 5, No, 1, p. 225, American Chemical Society, Division ofPolymer Chemistry, April 1964.

The following examples are given in illustration of the invention andare not intended as limitations thereof. All parts and percentages areby weight unless otherwise specified.

EXAMPLE 1 The polyester is prepared according to the followingprocedure:

Charge A (l) 150 ml. Water (2) 15 ml. of 10% sodium lauryl sulfatesolution in water (3) 2.0 g. sodium hydroxide pellets (4) 100 g. choppedice (5) 4 drops antifoam 6 Charge B (6) 0.025 mole of a 1:1 molarmixture of isophthaloyl chloride and terephthaloyl chloride (I/Tmixture) (7) 0.025 mole of the 2 butoxyethyl ester of 4,4-bis(4-hydroxyphenyl) pentanoic acid (8) ml. chloroform Charge A is placed in aWaring Blendor and the speed of the stirring regulated by a Powerstat.The solution is cooled to 3 C. by the addition of ice and the stirringincreased to the maximum. Charge B is then added quickly in one portion.If the temperature of the polymerization rises to 7 C., additional iceis added. The emulsion is stirred for five minutes. Then the solidpolymer is isolated either by pouring the emulsion into 1 liter ofmethanol or by adding methanol to the emulsion until coagulation occurs.The polymer is washed three or four times in the Waring Blendor with hotwater, and finally it is collected on a Buchner funnel Where it isWashed with methanol. The polyester is then dried in a vacuum oven at 55C./ 15 mm. for 1520 hours. A white product is obtained in a 68% yieldand a 0.5% solution in a 75:25 by volume mixture of phenol andtetrachlorethane has an inherent viscosity of about 0.63 at 30 C.Similar preparations in chloroform or methylene chloride also yieldpolymers having inherent viscosities of over 0.90 which areapproximately equivalent to a molecular Weight of about 40,000 to50,000. The softening point of these latter polymers is about -95" C.

A 4% by weight solution in chloroform of one of these I/T polyesters ofthe 2-butoxyethanol ester of 4,4-bis- (4-hydroxyphenyl)pentanoic acidhaving an inherent viscosity of 0.66 is prepared. This solution is caston a portion of a color photoprint (Kodacolor) and allowed to dry atroom temperature, forming a film with a thickness of 0.1 mil.

Similar color photoprints are partially coated with films ranging from0.1 to 0.45 mil in thickness. The prints are then irradiated with a 450watt Hanovia ultraviolet lamp at a distance of 25 cm. The unprotectedportions of the prints fade rapidly, with the various blue dyes beingthe first to show signs of fading. The unprotected portion is bleachedto a red-brown color after only 4 /2 hours. After 171 hours, thatportion protected With the polyester coating with a thickness of 0.1 milis just beginning to show fading of the blue component.

To compare the effectiveness of these polyphenyl esters with otherpolymers, a 1.5 mil film of poly(ethylene terephthalate) is placed overa portion of the color prints. Within 28 hours of exposure, as above,fading is noticed in the protected colors of the photoprints and thefilm itself becomes frosted and opaque.

Other comparisons are carried out using commercial acrylic resinscontaining 5%, by weight of resin, of standard monomeric ultravioletabsorbers. Film thicknesses of 2.0 mils on the photos show that fairprotection of the colors is possible for some period. However, theacrylic films become badly cracked and blistered. When these acryliccoatings are coated onto color photoprints at a thickness of 0.3 mil,fading occurs under the protected portion as rapidly as it does on theunprotected portion of the photo.

EXAMPLE 2 This polyester is prepared according to the followingprocedure for solution polymerization.

, Charge A (1) 2.14 g. butyl ester of 4,4-bis(4'-hydroxyphenyl)pentanoic acid (2) 2.06 g. resorcinol (3) 2.54 g. isophthaloyl chloride(4) 2.54 g. terephthaloyl chloride (5) ml. methylene chloride 7 Charge B(6) 7.2 ml. triethylamine Charge A is placed in a 2.50 ml. Erlenmeyerflask equipped with a water condenser and cooled to C. Charge B is addedslowly to the cooled A portion. The solution is agitated with a magneticstirrer for 4 hours during which time the temperature of the reactionmixture is allowed to rise to 25-30 C.

The resultant polymer is isolated by precipitating the polymer solutioninto an excess of methanol. The resin is washed once with methanol,twice with water and dried in a vacuum oven for hours at 70-80 C. Theproduct yield is about 98% and the polymer has an inherent viscosity of0.91 when run according to the procedure of Example 1.

A solution of the polymer in methylene chloride containing a smallamount of cyclohexanone (0.158 part in one part) is used to form a 1 milthick coating on a portion of coated paperboard coated with fluorescentdye paints. The coated paperboard is placed approximately centimetersbelow a 450 watt Hanovia U.V. lamp. The unprotected portion of thefluorescing paints loses its fluorescence within 6 minutes while thefluorescence of the protected portions remains essentially unchangedeven after hours. The colors in the paints also fade on the unprotectedportions while protection is greater than 90 for the coated portion.

Examples 3 to 22 illustrate the wide variety of aromatic dihydriccompounds that one may use in the practice of this invention as well asthe wide range of proportions of aromatic dihydric compounds to thosedihydric compounds illustrated by Formula I. The aromatic dicarboxyportion was a 1:1 mixture of isophthalic and terephthalic acid chloridesand was kept essentially constant in these examples. The results aretabulated in Table I. All ratios for the dihydric compounds are given inmoles. The inherent viscosities were run according to the procedure ofExample 1 using a 0.5% solution in a 75:25 by volume mixture of phenoland tetrachloroethane at 30 C.

TABLE I.EXAMPLES 3-22 TABLE I.-EXAMPLES 322Continued Percent ExampleDihydrlc compound yield Inh. visc.

8 /25 bisphenol-A/lauryMA-bis(4- 69 0.69

hydroxyphenyhpentanoate.

9 75/25 2,2-bis(4'-hydroxyphenyl)- 94 O. 83

butane/butyl-4,4-bis(4-hydroxyphenybpentanoate.

10 75/25 2,2-bis(4'-hydroxyphenyl)- 94 0.83

bntanellauryl-4,4-bis(4-hydr0xyphenyDpentanoate.

11 90/10 bisphenol-A/ethyl-4,4-bis(4- 95 0. 95

hydroxyphenyDpentanoate.

12 75/25 bisphenol-A/ethyl-et,4-bis(4- 84 1. 15

hydroxyphenyl)pentanoate.

13 26/75 bisphenol-A/ethylAA-bis(4- 98 1. 73

hydroxyphenybpentanoate.

14 25/75 bisphenol-A/2-butoxyethyl 85 O. 54

ester of 4,4-bis(4 -hydroxyphenyDpentanolc acid.

15 50/50 bisphenol-A/2-butoxyethyl 74 0. 64

ester of 4,4-bis(4"hydroxyphenyl) pentanoic acid.

16 50/50 bisphenol-A/4,4-bis 4'- 0. 21

hydroxyphenybpentanoic acid.

17 98/2 bisphenol-A/4,4-bis(4- 9O 0. 16

hydroxyphenyl) pentanoic acid.

18 91/9 bisphenol-A/4,4-bis(4- 89 0. 15

hydroxyphenybpentanoic acid.

19 /15 bisphenol-A/bntyl4,4-bis(4- 73 1. 09

hydroxyphenyDpentanoate,

25/75 resorcinol/buty1-4,4-bis(4'- 95 0.

hydroxyphenyl)pentanoate.

90/10 resorcinol[buty1-4,4-bis(4 93 0. 85

hydroxyphenyl)pentanoate.

75/25 2-methyl resorcinol/butyl-4,4- 91 0. 57

bis(4-pydroxyphenyl)- pentanoate.

In Examples 3 to 22 the aromatic dihydric compounds which correspond toFormula I are varied from 2 parts (Example 18) to 100 parts (Examples3-6) out of a possible total of 100 parts to illustrate the wide rangein proportions that one might use in the practice of this invention.

Examples 719 illustrate the use of compounds which correspond to thegeneral structure represented by Formula I in combination with (1)compounds represented by Formula II (Examples 7 to 19) and (2) dihydricphenols (Examples 20-22).

The inherent viscosities reflect the wide range of molecular weightsthat one might achieve in the practice E l Dh due m M Percielllg I h 45of this invention. An inherent viscosity of 0 .15 (cf. xamp e 1 y co pouy e n Example 18) corresponds to a molecular weight of about 3 flp y 9277 2,000 while the value of 1.73 (cf. Example 13) would pentanoate. I 11 h f b 200 000 4 ButyktA-bs(4-hydroxypl1enyl)- 37 0.59 lndlcate 1111026611 fir Welg t 0 f 1 1 bl -H 11 D 8110B Exampes 3 to 34 are setort in Ta e to i us- L l- ,4 i 4-h 1- 5 liiiiaiioaie. ydmxypheny) 83 O73 50 trate the wlde range of dicarboxy compounds that oneNN-PBHtQmPthylene'4i4'bisfi4" 72 may use in the practice of thisinvention as well as the hydroxyphenybgentanamide, 7 75 25 blsphenol-A/utyl 4,4-bis(4- 87 0.59 range in proportion of 1sophtha11c toterephthalic acids. hydroxyphenyl)Pemanoate- Ratios of reactants aregiven in terms of molar ratios.

TABLE IL-EXAMPLES 23 TO 34 Percent Inh. Example Dihydn'c compoundDicarboxyacid chloride yield vise.

23 Ethyl-4,4-bis(4hydroxypheny1- Terephthalic 96 1.9

pentanoate. A 24 Butyl-4,4-bis(4-hydroxyphenyl) Isophthahc 99 1. 5

pentanoate. 25 Ethyl-4,4-bis(4-hydroxyphenyl)-1=1=1isophthelic/terphthalic/oxy- 87 0.6

entanoate. dibenzoyl. 26 75 25 resorcinol/butylAA-bis (4-2-methoxyethanol ester of 34 0. 12

hydroxyphenyl)pentanoate. trimelli c. 27 do 1/1isophtalic/terephthalic92 1.10 28 ButyMA-bis(4-hydroxyphenyl)- 60/40 tert. bntyl isophthalic/91 0. 6

pentanoate. terephth in. 29. 93 0.7 30 l 95 1. 1 31. 82 0.5 32. yphenyl)85 0. 7

pentanoate. 33 d0 KetodlbenzoyL... 98 0.2 34Ethyl-4,4-bis(4-hydroxyphenyl) Isobutylidene 95 0.9

pentanoate.

Solutions of the polyester prepared in Example 1 In general, both theadhesion ability and the abrasion above were used to coat Kodacolorprints and color transresistance of these coatings has been surprisinglysatisparency slides in order to study the degree of protection factory.It has been found especially advantageous to prethat these polymersafford against the degradation caused pare copolymers of thesepolyesters using dihydric maby ultraviolet light. The U.V. stabilitytests are conducted terials which correspond to Formula I alone or incomby placing the test specimens about 25 cm. away from 5 bination withthe compounds represented by Formula II a Hanovia 450 watt U.V. lamp andobserving the degradaand with dihydric phenol types and at least onedi-acid. In tion of the test specimen as a function of time. thismanner, it is possible to obtain polyesters combining TABLE III.RESULTSOF U.V. STABILITY TESTS Results on substrate Polyester Exposure exampleSolvent Substrate time (hrs) Protected Unprotected 1 Methylene chlorldeKodacolor prints 7 90% color Colors faded.

retention.

1 Chloroform Color transparency slides 48 do Do.

The polyester Solutions may be applied by knife, spray, desirablesolubility of solution, with properties such as flow coater, curtaincoater, dip or brush to give a full film clarity and film strength. Theester derivatives of even coating. Free films may also be cast fromsolutions Formula I are especially useful in enhancing the soluof thesepolyesters. These films can be conveniently bility of the polymers.

laminated to photoprints using heat and pressure. A 0.5 Certainpolyesters which are not rearrangeable such as mil thick film ofrearranging polyester so laminated poly(Bisphenol-A carbonate) may givesome protection produced excellent protection from ultraviolet light. atwave lengths below about 300 m because of their aromatic nature.However, they given no protection above EXAMPLE 35 about 300 m and dodegrade at higher ultraviolet wave The rearrangement of the polyester ofpoly(ortholengths. In addition, because of their inability torearhydroxybenzophenones) was Studied in the following range, they lackthe ability to renew themselves. Polymanner. styrene is known also tofurnish some protection against A 0.50 mil film of the polyester ofExample 1 is cast U.V. light below about 300 mg. However, it is not onglass from a 10% solution in toluene. The clear, transstable to U.V.light about 300 m and so its protective parent film is placed directlybelow a Hanovia lOO-watt action is short lived. In contrast thereto,poly(methyl U.V. lamp and after various time increments, IR spectramethacrylate) doesnt protect substrates from U.V. light of the film areobtained. These spectra are obtained both but is relatively stablethereto. The present polyesters for the exposed side and for theunexposed side of the are superior to a combination of the bestultraviolet propirradiated film by means of an attenuated totalreflectance erties of these two preceding materials.

(ATR) attachment for a Beckman IR-5 spectrophotom- Othernonrearrangeable polyesters have been formed eter. Proof of therearranged structure is obtained by using2,2-bis(3,5-dimethyl4-hydroxyphenyl)propane as measurement of the bandsin the region 2.0 to 15 the phenolic material with a mixture ofisophthalic and The absorbance of the new benzophenone carbonylterephthalic acids, as well as polyesters derived from subpeak formed at6.12 by the irradiation is divided by the stituted fumaric acid withBisphenol-A. These do not con- C-H absorbance at 3.35 using a standardbaseline method tain an unsubstituted position ortho to the hydroxygroup.

to give a relative value for the amount of carbony Certain monomericmaterials may be usable but prefpresent. The initial value of zero ofthis proportion, erably only in small amounts because they may adverselygradually grows to 0.15 on 15.5 hours of irradiation, to affect thesolubility of the products formed or inhibit the 0.40 after 70 hours andstarts to level off at approximately polymerization by limiting theproducts to low molecular 0.58 after about 175 hours. This levelling isbelieved due weight. Such materials include ortho-phthalic acid and tothe fact that the surface polymer molecules have recatechol or materialscontaining crosslinkable groups.

arranged to ultraviolet absorbing groups, thus prohibiting Thepolymerization of these polyesters is conducted any further ultravioletradiation from penetrating the with a non-reacting organic liquid whichis a solvent film. No changes from the original polyester film are forboth the monomers used and the polymers produced found on the unexposedside. in order to achieve the high molecular weights desired. The U.V.lamp used for irradiation in this example is a When using interfacialcondensation, the organic solvent Hanovia 100-watt high pressure quartzmercury-vapor must be capable of furnishing a twophase system with lamp,model 608A. The lamp is 25 cm. above the film. the second liquid. Suchsolvents may be selected from The approximate intensity of theultraviolet radiation at those which are used as the solvents in thesolution coat- 336 m reaching the film is 100 microwatts/cm. The ingcompositions containing these various polyesters. The total output ofU.V. radiation from the lamp is 4.64 solubility and solution stabilitywill, of course, vary for watts which represents 40.3% of the totalradiation each polymer with different solvents, and in some inemitted,the remaining 59.7% consists of visible and instances, mixtures ofsolvents are preferred. Some of the frared radiation. solvents used forcoating compositions include aliphatic The rearranged polyester isstable to ultraviolet radiaand aromatic halogenated hydrocarbons such aschlorotion without undergoing apparent chain scission or crossform,methylene chloride, ethylene chloride, chlorobenlinking for at least1,000 hours under the above condizene; aromatic and aliphatic ketonessuch as methyl ethyl tions. Samples so exposed are found still solublein chloketone, cyclohexanone and acetophenone; aromatic hyroform andshowed no appreciable change is viscosity. drocarbons such as benzene,toluene and xylene; di-substi- Additional proof of the rearrangedstructure is obtained tuted amides such as dimethyl acetamide; aromaticesters by measuring the band intensities with an ultraviolet such asphenyl acetate; aliphatic amines such as N-methyl; spectrophotometer.aromatic amines such as pyridine; aromatic ethers such as When a film ofpoly(Bisphenol-A carbonate) is simidibenzyl ether, diphenyl ether;aliphatic cyclic others such larly irradiated for 800 hours, an IRspectrum shows no as phenols; aliphatic and alicyclic sulphoxides andsulnew bands in the region 5.8-6.2 Obviously, all aromatic phones suchas dimethyl sulfoxide, 1,1-dioxy-tetrahydropolyesters do not undergothis rearrangement, but rather thiophene; and unsaturated alkylaromatics such as they require a judicial selection of monomers andpostyrene. Others include Z-ethoxyethyl acetate, Z-methoxylymerizationconditions. An aromatic polyester of 2,2-bisethyl acetate,2-butoxyethoxyethanol, tetrahydrofuran, di-(3,5'-dichloro-4-hydnoxyphenyl) propane and isophthalic acetone alcoholand N,N-dimethyl formamide. acid similarly fails to show evidence ofrearrangement on The chlorinated hydrocarbons such as methylenechloirradiation, ride and chloroform are especially preferred both aspo- 11 lymerization solvents and as solvents for the coatingcompositions. Aromatic solvents such as toluene are also especiallyuseful solvents for forming coating compositions from a variety of thesepolymers.

The coating compositions of this invention capable of forming clearfilms which are stable to and adsorb ultra violet light comprisesolutions of about 0.5% to about 75% of a polyaromatic polyester in avolatile organic solvent having a boiling point of about 40 C. to about200 C. These aromatic polyesters having molecular 1 O O (])11 r t I C Ia. l tiggfg I- H (IV) These polymers are formed by rearrangement causedby ultraviolet light of another layer (2) of polyesters of a molecularweight of at least 3,000 having repeating units of a structural formula:

nwgtao wherein R, R R and R are as heretofore defined, A is thedicarboxylic acid moiety and n is an integer of from 1 to 8, x is aninteger of from 5 to 70, y is an integer of from 0 to 65 and z is aninteger of from 0 to 65, wherein the total of y and z is not greaterthan 65, and wherein polymer layer (1) is the layer exposed to theultraviolet light and is the rearrangement product of the polyester (2).

The aromatic polyesters of this invention are soluble in organicsolvents. Solutions of these aromatic polyesters form clear adherentcontinuous coatings, which on exposure to ultraviolet light rearrange onthe exposed surface to form ultraviolet stable layers, which are alsoopaque to ultraviolet light. These rearranged layers must containrecurring units comprising 2 aromatic groups, such as phenol joined bythe carbon of a carbonyl group, at least one of the aromatic groupshaving a hydroxyl group ortho to the carbonyl linkage. The remainingnonrearranged polyester resin is protected from the ultra violet lightby the rearranged layer. However, on weathering or other removal of theeffects of the rearranged layer, the polyester functioning as areservoir readily forms new rearranged layers on exposure to ultravioletlight.

This invention has been described above; however, it is not so limited.Variations and modifications such as pigments, dyes, fillers, resinousadditives, stabilizers, may be added to the polyesters or solutionsthereof without departing from the spirit or scope of this invention.

What is claimed is:

1. A photoprint protected from ultraviolet light with 'a clear adherentcoating of two contiguous superposed layers: (1) an outer layer having athickness of at least a monomolecular layer, said layer being anaromatic polymer having at least one hydroxyl group in an ortho positionto at least one ketone group in each polymer unit, said polymercomprising repeating units of the structural formula:

2 on 0 o o T H I] II C C R1CR7 Biz itgtlo ll L y L 1. wherein R isselected from the group consisting of hydrogen and alkyl groups of from1 to 6 carbon atoms, R is an alkylene group of from 1 to 10 carbon atomsand R is selected from the group consisting of amino, alkoxys of from 1to 18 carbon atoms, and OR.;

-N=R wherein each R is an independently selected alkylene group of from1 to 10 carbon atoms, R; is an aryl group of from 6 to 10 carbon atoms,each R is independently selected from the group consisting of hydrogen,alkyls of;-from 1 to 6 carbon atoms, and aryls of from 6 to 10 carbonatoms, R is a divalent aliphatic radical of from 2 to' 10 carbon atoms,R, is independently selected from the group consisting of hydrogen andalkyl groups of from 1 to 6 carbon atoms, A is a dicarboxylic acidmoiety and n is an integer of from 1 to 8, x is an integer of from 5 to70, y is an integer of from 0 to 65 and z is an integer of from 0 to 65,wherein the total of y and z is not greater than 65, and wherein polymerlayer (1) is the layer exposed to the ultraviolet light and is therearrangement product of the polyester (2).

2. A coated photoprint as in claim 1 wherein the polyester is' thepolymerization reaction product of (a) a mixture of 25 to 75 mol percentof resorcinol and 75 to 25 mol percent of an alkyl ester of 4,4- bis(4-hydroxyphenyl)pentanoic acid wherein the alkyl group contains from 1to 18 carbon atoms; and

(b) a mixture of from 30 to 70 mol percent isophthalic acid and 70 to 30mol percent terephthalic acid.

3. A coated photoprint as in claim 1 whrein the photoprint is a coloredphotoprint.

4. A coated photoprint as in claim 1 wherein the photoprint is a coloredslide.

5. A coated photoprint as in claim 1 wherein the photoprint is a blackand white photoprint.

6. A photoprint protected from the ultraviolet light with a clearadherent coating of two contiguous superposed layers comprising:

(I) an inner layer in contact with the photoprint, the

inner layer being a rearrangeable polyester having a molecular weight inthe range of from 3,000 to 200,000 which comprises the polymericreaction product of: 1

(A) from 10 to 100 parts, based on a total of 100 parts of (A) and (C),of an aromatic dihydric compound having at least one unsubstitutedposition ortho to an aromatic hydroxyl group wherein the aromaticdihydric compound corresponds to the general structural formula:

wherein R is selected from the group consisting of hydrogen and alkylgroups of from 1 to 6 carbon atoms, R is an alkylene group of from 1 to10 carbon atoms and R is selected from the group consisting of alkoxysof from 1 to 18 carbon atoms, and O(R OR -l H, wherein each R is anindependently selected alkylene group of from 1 to 10 carbon atoms and nis an integer of from 1 to 8,

(B) at least one aromatic dicarboxyl compound capable of esterification,which is selected from the group consisting of aromatic dicarboxylicacids and acid halide derivatives thereof which are selected from thegroup consisting of unsubstituted and halo and alkyl substituted (1)terephthalic acid, isophthalic acid, di-

phenic acid, binaphthyl dicarboxylic acid;

(2) the acid halides of the foregoing acids;

and

(3) acids and acid chlorides which correspond to the general structuralformula:

wherein X is selected from the group con sisting of hydroxyl or halideand R is selected from the group consisting of methylene, carbonyl,oxygen, sulfur, sulfone, isopropylidene, isobutylidene and ethylidene;and (C) from zero to parts, based on a total of parts of (A) and (C), ofan aromatic dihydric compound selected from the group consisting of 1)an aromatic dihydric compound having at least one unsubstituted positionortho to an aromatic hydroxyl group, wherein the aromatic dihydriccompound corresponds to the general formula:

HO R1 OH 1.

wherein each R is independently selected from the group consisting ofhydrogen and alkyl groups of from 1 to 8 carbon atoms; and (2) adihydric phenol, the total quantity of (A) and (C) being substantiallystoichiometrically equivalent to the quantity of (B); and

(II) an outer exposed layer in contiguous superposed relationship to theinner polyester layer, said outer layer having a thickness of at least amonomolecular layer which outer layer is the ultraviolet lightrearranged product of the inner polyester layer.

7. A coated photoprint as in claim 6 wherein the photoprint is a coloredphotoprint.

8. A coated photoprint as in claim 6 wherein the photoprint is a coloredslide.

9. A coated photoprint as in claim 6 wherein the photoprint is a blackand white photoprint.

10. A photoprint protected from ultraviolet light with a clear adherentcoating of two contiguous superposed layers comprising:

(1) an inner layer in contact with the photoprint, the inner layer beinga rearrangeable polyester having a molecular weight in the range of from3,000 to 200,000 which is the polymeric reaction product of (A) from 10to 100 parts based on a total of 100 parts of (A) and (C) of an alkylester of 4,4-bis- (4'-hydroxyphenyl)pentanoic acid wherein the alkylgroup contains from 1 to 18 carbon atoms;

(B) a mixture of isophthalic acid and terephthalic acid; and

(C) from zero to 90 parts based on a total of 100 parts of (A) and (C)of resorcinol, the total quantity of (A) and (C) being substantiallystoichiometrically equivalent to the total quantity of (B); and (2) anouter layer which is the ultraviolet rearranged product of the innerpolyester layer. 11. A photoprint protected from ultraviolet light witha clear adherent coating of two contiguous superposed layers: (1) anouter layer having a thickness of at least a monomolecular layer, saidlayer being an aromatic polymer having at least one hydroxyl group in anortho position to at least one ketone group in each polymer unit, saidpolymer comprising repeating units of the structural formula:

OH 0] I C i 01 L 2L 1 wherein R is selected from the group consisting ofhydrogen and alkyl groups of from 1 to 6 carbon atoms; R is an alkylenegroup of from 1 to 10 carbon atoms; R is selected from the groupconsisting of amino, alkoxys of from 1 to 18 carbon atoms; O{-R OR-},,H, and

Ills

wherein each R is an independently selected alkylene group of from 1 to10 carbon atoms and each R is independently selected from the groupconsisting of hydrogen and alkyls of from 1 to 6 carbon atoms; R, isindependently selected from the group consisting of hydrogen and alkylgroups of from 1 to 6 carbon atoms; and n is an integer of from 1 m8; xis an integer of from 5 to 70; y is an integer of from 0 to and z is aninteger of from 0 to 65; wherein the total of y and z is not greaterthan 65, and wherein polymer layer (1) is the layer eX- posed to theultraviolet light and is the rearrangement product of the polyester (2).

12. A coated photoprint as in claim 11 wherein R is -O{-R -O-R H,wherein each R is an independently selected alkylene group of from 1 to10 carbon atoms and n is an integer of from 1 to 8.

References Cited UNITED STATES PATENTS 2,907,736 10/ 1959 Greenlee.

2,933,520 4/1960 Bader.

3,160,602 12/ 1964 Kantor et 81.

3,309,334 3/1967 Holub.

3,322,555 5/1967 Himmelmann et a1. 117-45 X 3,365,295 1/1968 Nittel etal 1l733.3 X 3,415,670 12/1968 McDonald 11733.3 X

MURRAY KATZ, Primary Examiner R. HUSACK, Assistant Examiner U.S. Cl.X.R.

@2233? UNITED STATES PATENT omen CERTIFICATE OF CORRECTION Patent No.3,506,470 Dated April l4, I970 Imnntor) Raymond H. Young, Jr. Saul M.Cohen, Alberl H. Markhar'r, &

lrvln Serl in It 1: certified that error appears in the ebove-identif edpatent and that said Letters Patent are hereby corrected el shown below:

Column 8, Table 2, Example 25, l=l=]" should read l l I Column I I ine6, "adsorb" should read absorb Claim l 1, Column I6, I ine I l l'hesubscrip+ oul's ide the brackel' in The fif'l'h formula should bechanged from "2" 1'0 y Claim I l Column I6, I ine l I, the subscriptourside +he bracke1 in l'he six+h formula should be changed from "x" +0z 3mm SEALED (SEAL) Amt:

m, mm: x. 1 i f h Gomlssioner or PM ttemng Offic

